The present invention relates to a device for holding a rod-shaped object through an operating mechanism utilizing spring coil characteristics and, more particularly, this invention is provided with a multi-stage integrated continuously coiled spring placed in an operating mechanism, and said spring is actuated to enlarge to a proper calibre by means of said mechanism or is restored to its original condition by its own resilience.
The conventional clamp-holding for a rod-shaped object is generally effected by a three-claw attachment; for example, the fixture of a whole set of screwdrivers and the three-claw fixture of thread-tap and so on. Said three-claw attachment needs a high precision. The cost is high, and in addition, during operation, said claw attachment must be firstly loosened and then screwed tight after the rod-shaped object is inserted. It requires a considerable effort in operation and is difficult to be quickly set for precise centerization.